Chapter Ten Day Four

Paired t Procedures

Homework

p. 657 33,34,36

p. 659 37,38,40,42,44

Our subjects are 11 people diagnosed as being dependent on caffeine. Each subject was barred from coffee, colas, and other substances containing caffeine. Instead, they took capsules containing their normal caffeine intake. During a different time period, they took placebo capsules. The order n which subjects took caffeine and the placebo was randomized. We will construct and interpret a 90% confidence interval for the mean change in depression score.

Example

Subject Depressionplacebo

DepressionCaffeine

DepressionPlacebo - caffeine

1 16 52 23 53 5 44 7 35 14 86 24 57 6 08 3 09 15 210 12 1111 0 1

Results of Caffeine-deprivation Study

Parameter of Interest:

Conditions

Calculations

Interpretation

An inference procedure is called ROBUST if the probability calculations involved in that procedure remain fairly accurate when a condition for use of the procedure is violated. For confidence intervals, this means that the stated confidence level is still fairly accurate.

t procedures are NOT robust against outliers

Robust Procedures